Vehicle seat belt alarm and starter interlock control system

ABSTRACT

A source of voltage is connected to a starter interlock through a normally open seat switch and a first normally closed seat belt actuated switch. Closing of the seat switch when a passenger sits connects the voltage to the interlock and disables the starter mechanism. Buckling the seat belt opens the seat belt actuated switch and enables the starter mechanism. The voltage is also connected to the starter interlock through the series combination of the normally opened seat switch and a normally closed relay switch. Battery voltage is coupled to the relay switch coil through a second normally open seat belt actuated switch and a capacitor in series. Buckling of the seat belt causes a pulse of current to be transmitted through the capacitor to energize the relay coil thereby opening the normally closed relay switch. A holding circuit through the seat switch maintains the relay switch open. Thus, the seat belt must be buckled after sitting down in order to provide the pulse of current to initially close the relay switch and to provide the continuing current to keep the relay closed. While the vehicle is in use, a warning buzzer and warning light are actuated by the same voltage source which disables the starting circuit.

United States Patent 1 Pearsall [45] Feb. 27, 1973 Q [54] VEHICLE SEATBELT ALARM AND STARTER INTERLOCK, CONTROL SYSTEM I [75] Inventor:Gerald'Robert Pearsall, Farmington, Mich.

[73] Assignee: Irvin Industries Inc, Greenwich.

Conn. 22 Filed: Dec. 6, 1971 211 App]. Nos-205,209

[52] U.S. Cl. ..340/52 E, 340/278, 307/10,

180/82C [511' Int. Cl ..B60r2l/l0 [58] Field ofSearch .340/52 E, 278;307/10; l80/82C [56] I References Cited UNITED STATES PATENTS 3,340,s239 1967 'Whitman-.. ..'.......-....34o/27s 1 3,449,714 6/1969 Farley,Jr........; ..340/52 E Primary Examiner-Alvin H: Waring Attorney-Lloyd YMcAulay' ABSTRACT A source of voltage is connected to a starterinterlock through a normally open seat switch and a first normallyvclosed seat belt actuated switch. Closing of the seat switch when apassenger sits connects the voltage to the interlock and disables thestarter mechanism.

Buckling the seat belt opens the seat belt actuated switch and enablesthe starter mechanism. The voltage is also connected to. the starterinterlock through the series combination of the normally opened seatswitch and a normally closed relay switch. Battery voltage is coupled tothe relay switch coil through a second normally open seat belt actuatedswitch and a capacitor in series. Buckling of the seat belt causes apulse of current to be transmitted through the capacitor to energize therelay coil thereby opening the normally closed relay switch. A holdingcircuit through the seatswitch maintains the relay switch open. Thus,the seat belt must be buckled after sitting down in orderto provide thepulse of current to initially close the relay switch and to provide thecontinuing current to keep the relay closed. While the vehicle is inuse, a warning buzzer and warning light are actuated by the'same voltagesource which disables the starting circuit.

l6 Claims, 3 Drawing Figures g VEHICLE SEAT BELTALARM AND STARTERINTERLOCK CONTROL SYSTEM This invention relates in general to a systemfor requiring that a seat belt be closed before an automoseat belt isbuckled about the passenger before the vehicle can be started.

BACKGROUND OF THE INVENTION At the time of this invention, the usage ofan electrical switch which had to be actuated by the fastening of theseat belt asa prerequisite to turning on the car motor, was known. Onesuch system is described in pending patent application Ser. No. 85,343,filed Oct. 10, 1970, and entitled Safety Seat Belt System, whichapplication is assigned to the assignee of the instant application.Briefly, the above-referenced application describes a system in which anormally opened seat switch is closed when a passenger (the driver whenhe sits in the driver's seat or some non-driver passenger in otherseats) sits down. The closing of this normally opened seat switchcompletes an electric circuit that energizes a relay in a starterinterlock circuit, which relay in turn opens the starter circuit. Theseat belt associated with the seat having the seat switch operates asecond switch. When the seat belt is fastened, the seat belt actuatedswitch performs a circuit function that deenergizes the relay in thestarter interlock circuit. The deenergization of the starter interlockrelay enables the-starter circuit and the car's starter motor can beturned on. A major limitation of the usefulness of such a seat belt andstarter interlock system is that it can be readily defeated by havingthe seat belts maintained in a coupled or fastened position regardlessof whether or not a passenger is in the seat involved. The driver and/orpassengers'simply sit on the buckled belts or ignores them wheneverentering the-car. Because the coupled seatbelts results in ade-energized starter in-' terlock 'relay, the driver sitting on his seatand closing his seat switch has no effect on the disabling interlockrelay because-the circuit that would energize the disablingrelayismaintained open by virtueof the fact that the seat belt is maintainedcoupled.

Accordingly, it is a major purpose of this invention to provide animprovement in the seat belt starter interlock system that will preventdefeating the system by keeping the seat belt continuously coupled. i

More particularly, it is a purpose of this invention to provide animproved system that will require the fastening of. the seat belt afterthe driver or other passenger has sat down in the car; Y

It is a further and important purpose of this invention that'the abovepurposes be achieved with a system that is simple, inexpensive andreliable so that its'use will be acceptable to both automobilemanufacturer and purchaser. I

It is a further related purpose of this invention to provide such animproved systemthat will besufficiently difficult to defeat orcompromise so that the driver and passenger will find it more convenientto fasten the seat belt around themselves rather than go to the troubleof compromising or ignoring the system.

BRIEF DESCRIPTION OF THE INVENTION In brief, this invention involves theuse of a capacitor to couple one side of a seat belt actuated switch tothe coil of a relay switch. The other side of the seat belt actuatedswitch is connected to the automobile battery. When the seat belt isuncoupled, the battery is not connected to the capacitor. Thus, in theprocess of buckling the seat belt a pulse of current is applied to thecapacitor and, because it is a pulse, applied through the capacitor tothe coil of the relay switch to energize the relay switch. The relayswitch when not energized provides a closed circuit (through the relayswitch contacts) between the seat switch and the starter interlock. Theseat switch when closed, as when a driver or passenger is seated in thecar, connects battery voltage to the relay switch contacts and, when therelay switch is not energized, through the relay switch contacts to thestarter interlock. This battery voltage at the input to the starterinterlock energizes and thus opens the normally closed interlock relaythereby opening the circuit between the start switch and the startersolenoid so that the car cannot be started. a

The only way, then, to start the car is to buckle the seat belt whichwill providea pulse of current through the capacitor to the relaycoilthereby switching the state of the relay switch and opening thecircuit between the seat switch and the starter interlock.

A holding circuit in the relay switch maintains the 'relay switchenergized after the pulse of current has initially energized the relayswitch.

If the seat belt is maintained in a buckled condition on a continuousbasis, including when the car is not in use, for the purpose ofdefeating this requirement that i the seat belt be buckled toenergizethe relay switch,

then what happensis that after the driver or passenger is seated thestarter interlock has voltage applied to it to open the starterinterlock. But no pulse of current is applied to the capacitor becausethere is no buckling of the seat belt andthus no change in the voltageon the capacitor to provide a pulse that can be transmitted through thecapacitor to the relay coil. All thathappens is that the battery voltageapplied to the capacitor is a steady state voltage that isblocked by thecapacitor from access to the coil of the relay switch. To start thevehicle will then require'unbuckling' the seat belt and rebuckling it. I

BRIEF DESCRIPTION OF THE DRAWINGS second embodi- DESCRIPTION OF THEPREFERRED EMBODIMENTS.

Normal Operation of the FIG. 1 Embodiment FIG. 1 is an electricalschematic'of a preferred embodiment of the device of this invention. Asshown therein,'a battery 10 is connected to one terminal of a normallyopened seat switch 12. Assuming that the seat switch 12 is the switch inthe seat used by the driver, then when the driver enters the car andsits down, his weight will close the switch 12. On closing the switch12, the positive terminal of the battery is connected to a first switcharm 16a of a seat belt actuated switch 16. When the belt is unbuckled,the switch arm 16a has the state shown in solid line in FIG. 1 Thus,when the driver sits down, he closes the seat switch 12 and batteryvoltage is connected through the switch arm 16a to starter interlock 20.

When a voltage is applied as an input to the starter interlock 20, anormally closed relay (not shown) in the interlock 20 is opened to openthe circuit through the interlock 20 so that the closing of the startswitch will not apply voltage to the starter solenoid and the car cannotbe started.

In addition, if the driver turns the transmission setting from eitherthe park or neutral position 1, N to either the drive or reverseposition D, R, then the switch arm 22 will be moved from the openposition, as shown, to a closed position. With the drivers seat switch12 closed, this will complete a circuit through the point 18 thatapplies voltage from the battery 10 to I 'a warning light 24 and to awarning buzzer 26 to provide visual and auditory indications to thedriver that the seat belt has not been connected and that the car cannotbe started. I

Now, if after the driver has seated himself, he then fastens the seatbelt, the state of the seat belt switch 16 position shown in dotted linein FIG. 1. Such a change in the position of the switch arms of the seatbelt actu-.

I ated switch 16 does two things.

First, the change in position of switch arm 16a opens the path along theline 17 from battery 10 to point 18 and at the same time connectsbattery 10 to point 18 through the line 19 and relay arm 14a.

Second, the change in position of switch arm 16b applies battery voltagethroughthe switch arm 16b to the capacitor C. Because of this switchingaction of the switch 16, the voltage applied to the capacitor C is seenas the leading edge of a pulse that is transmitted through the capacitorC and to the coil 14c of the relay switch 14. Since it is a positivepulse, the diode D will not conduct. This pulse energizes the coil 14cand switches the state of the relay 14 from that shown in solid line inFIG. 1 to the state shown in dotted line in FIG. 1.,

' The switching of the relay switch 14a causes B+ voltage to be appliedon the line 19 from the battery 10 to the coil 14c, thereby providing aholding circuit so that the coil 14c stays energized even though thepulse of I current transmitted through the capacitor C terminates; .Theswitching of the relay switch arm 14a further results in opening thecircuit through the line 19 j from. the battery 10 to the point 18. As aresult, the

voltage at the point l8 drops and the starter interlock 20 isde-energized, thereby closing the circuit through the interlock 20 sothat actuation of the start switch will start the motor. At the sametime, since there is no longer voltage at the point 18, the switching ofthe switch arm 22 from the park or neutral P, N position shown to thedrive or reverse D', R position does not light the light 24 nor causethe buzzer 26 to sound. Assuming the Seat Belt 15 Left BuckledPermanently (FIG. 1)

The above is a description of the normal operation of this invention.However, the important point about the relationship of the elementsshown is that they serve to inhibit any attempt to defeat the purpose ofthis system which is to cause a driver to fasten his seatbelt. Assume,therefore, that the seat belt actuated switch 16 is placed in thebelt-on" state by fastening the seat belt and causing the seat belt tolie on the seat without having it around the driver. When the driverthen gets into the car and sits down, he closes the seat switch 12 whichthen applies voltage to the'point 18, through the switch arms 16a, 14a,thereby opening the interlock 20.

Now, since the battery 10 has been connected all along, through theswitch arm 16b, to the left side of the capacitor C, there is no way inwhich to energize the relay coil 140. Thus there is'no way to change thestate of the relay switch 14 and the car cannot be started. The drivermust open the seat belt and close it againin order to get a pulse ofcurrent through the capacitor C toswitch the state of the relay 14. Onlythen willvoltage be removed from the point 18 because of the switchingof relay arm 14a. Accordingly, the use of the capacitor C in theposition shown in combination with the seat belt switch 16, relay switch14 and seat switch 12 creates a condition which tends to assure that thedriver will buckle the seat belt around himself because it is simplierto do such than to try to defeat the purpose of the system. 1 The DualArm Seat Belt Actuated Switch (FIG. 1)

The seat belt actuated switch 16 hastwoswitch-arms 16a and 16b thatperform two separate functions. The function of the switch arm 16a is toassure that the seat belt is infact buckled when the motor'isstarted.'The function of the switch arm 16b is to make sure that theseat belt is buckled after the driver has been seated and has closed theseat switch 12. These are two' different functions. The former functionis a state function and the latter function is a sequencing function.Unless both functions are provided, it is possible for the driver todefeat the system without actually maintaining the seat belt buckled.

For example, in one embodiment, the seat belt actuated switch 16 is inthe retractor mechanism. In that embodiment, the act of pulling the seatbelt web out of the retractor rotates a cam that throws the switch 16from the belt-off position shown in FIG. 1 to the belt-on position.Thus, if the driver were simply to pull out the web'an adequate distanceand'let it fall back he would switch the arm 16b to' the contact 16d,provide apulse to the capacitor C and succeed in energizing the coil 14cand thus would open the circuit through-therelay arm 14a to the point 18from the seat switch 12. But

with the existence of the contactarm 16a as shown, it

the point 18 will open the interlock 14 to prevent the motor from beingstarted. However, under that condition, the 2,000 ohm resistor willprevent enough current from flowing through to actuate either the buzzer26 or light 24.

During operation of the vehicle, the switch 22 is closed and anyunbuckling of the seat belt will cause battery voltage to be appliedthrough the switch arm 16a over the line 17 to the point 18 and thusthrough the switch 22 to turn on the warning light 24 and sound thewarning buzzer 26.

The relatively high resistance resistor R serves to make sure that anyleakage, such as through the interlock 20, is bled to ground during theoperation of the vehicle. This makes sure that there is no unwantedbuild-up of voltage at the point 18 during normal operation. Thiscondition might occur where the interlock is solid state circuitry. TimeDelay Feature The relay 14 preferably has a time delay feature thatdelays the opening of the relay 14 when voltage is removed from the coil14c. This time delay feature is important to avoid unnecessarily causingthe buzzer 26 to sound and the light 24 to turn on duringthe normaloperation of the vehicle when the seat switch 12; might momentarilyopen. If the vehicle were being driven over a bumpy road, the drivermight be lifted off his seat sufficiently'to open the switch 12, Withoutthe time delay feature this wouldcause a distracting and undesirablewarning-sound. Indeed, if the seat switch 1 12 were so opened,theholding circuit to the coil 14c would be broken and the relay switcharm 14a would then close the circuit to thepoint 18. The subsequentclosing of the seat switch 12 would cause a continuing action of thewarning light 24 and buzzer 26, requiring that the seat belt beuncoupled and recoupled in order to provide an energizing pulse for therelay coil 14c.

One means of providing this time delay feature is for the arm 14a to bemade of bi-metallic material. A heating element 35 (see FIG. 3) ismounted on the arm 14a and is connected at one end to ground and at theother end to the point 30, which point 30 is the high voltage end of therelay coil 140. When the switch arm 14a is in the position shown in FIG.1, no battery voltage is applied to the relay coil and thus the heatingelement around the switch arm 14a receives no current and the switch arm14a is cool. Whenthe relay coil 14c is energized, the arm 14a is.ele'ctromagnetically switched to the position shown in dotted lines inFIG. 1. Once in that position, the relay is held in its energized stateby the holding circuit through the belt-on position of the .switch arm16a. The heating coil is thus connected across the battery and heats thebi-metallic switch arm [4a. This causes the switch arm 14a to bendtighter against the contact 31. When the seat switch 12 is opened, theheated bi-metallic arm 14a remains against the contact 31 for a periodof 5 to 10 seconds before cooling off and snapping open; Thisheating'element 35 is shown separately in FIG. 3 and is omitted fromFIGS. 1 and 2'in-orderto avoid confusion in illustration.-

Alternatively to a bi-metallic contact 14a, time delay can beestablished by switching in a capacitor across thecoil 14c when the coil140 is energized. I

The grounding of the switch arm 16b is important to make sure that thevoltage on the capcitor C is bled off when the seat belt is opened sothat the subsequent buckling of the seat belt will be effective toprovide a When the seat belt is being opened, the diode D 1 togetherwith switch arm 16b completes a .circuit through ground allowing areverse surge of current through capacitor C until both sides of thecapacitor C are at ground voltage thus preparing the capacitor for thenext surge of current when the seat belt is again buckled.

The above description has been made assuming that the seat switch 12 andseat belt actuated switch 16 were associated with the drivers seat. Oneof the advantages of the FIG. 1 embodiment is that the entire circuitarrangement upstream from the point 18 can be duplicated for as manyseats in the vehicle as it is desired to cover by this seat beltinterlocking arrangement. A separate seatswitch 12, seat belt actuatedswitch 16, capacitor C, relay switch 14 and other associated circuitrywould have to be provided for each passenger seat to be covered. Eachsuch circuit atrangement would then be connected to the point 18. If anyone of they seats thereby covered had a passenger who did not properlybuckle his seat belt, the resulting voltage at the point 18 would openthe starter interlock 14. Each of the passengers would have'to seathimself and then buckle his seat belt in order for the point 18 to havethe required zero'voltage level that permits starting the motor.Similarly, if anyone of the passengers opened his seat belt during theuse of the vehicle, the resulting voltage at point 18 would cause thelight 24 and buzzer 26 to operate.

The capacitor C in one embodiment is 600 microfarads and the resistanceof the relay coil'14c is 1,575 ohms. Use of a capacitoras large as thisprovides a RC time constant sufficiently great so-that relay 14 will notbe turned on by relatively small voltage fluctuations that might beinduced in the system and transmitted through the capcitor C. Forexample, the use of a capacitor as large as indicated means that anexpedient such as flashing the lights on and off will not provide apulse that might energize therelay coil 14c.

Although the above description illustrates an electromechanical relay14, it should be understood that other relays, including a solid staterelay could be employed. It should also be understood that the seat beltactuated switch 16 could be positioned and actuated in anumber offashions. For example, the switch 16 could require completion of thebuckling. Alternatively, the switch 16 could be in the retractormechanism and actuation of the switch occur when the webbing is pulledout of the retractor by a predetermined amount. In-

deed, the switch arms 16a and 16b could well be asis possible to limitthe switching of the switch arm 16b to a short period of time during theprocess of buckling. For example assume the case where this switch 16 isactuated by pulling the web out of the seat belt retractor. It isfeasible for a cam that actuates solely the switch arm 16b to actuatethe switch arm 16b at the point where the web is approximatelyone-fourth of the distance out of the retractor and then to have theswitch arm 16b return to the position shown in FIG. 1 when the web isthree-fourths of the distance out of the retractor. The result'would bea pulse of currentthat will switch the state of the relay 14.

It should further be understood, particularly with reference to theclaims, that the state of the seat belt actuated switch 16a when theseat belt is unbuckled refers to the condition where the seat belt webis completely returned to the retractor or is in whatever normalcondition exists after unbuckling. Similarly, the state of the seat beltactuated switch 16a when the seat belt is buckled is the state when theseat belt is completely and normally buckled. Obviously, the transitionbetween these two states may well occur during the process of buckling.This is particularly true where the seat belt actuated switches areactuated by .the movement of the webbing out of the retractor. But

is is the normally buckled and normally unbuckled end conditions thatare referred to herein. Alternate Embodiment (FIG. 2)

FIG. 2 illustrates a variant of the FIG. 1 embodiment which is lesspreferred because it can be conveniently used only in connection withthe drivers seat. In FIG. 2, the same reference numbers are used as inFIG. 1, where the parts are identical. When the part differs, a parallelreference number, one hundred higher in FIG. 2, is used.

In FIG. 2 the starter interlock 120 includes a normally opened relaythat is closed upon receipt at the input terminal of battery voltage.Only when this normally open interlock is closed can the start switchserve to energize the starter solenoid and turn on the motor.

. In this FIG. 2 embodiment, the 'relay switch 1 14 must have two switcharms, as shown. The holding circuit for the coil 114e is providedthrough the bi-metallic switch arm 114b andthe switch 16a when in thebelt-on position..

' In the FIG. 2 arrangement, the only way to apply battery voltage tothe starterinterlock 120 to close the starter interlock 120 is to closethe seat switch 12 and energize the relay 114 so that the switch arm114f is switched from the position shown in solid line in FIG. 2. Innormal operation, the driver takes his seat and closes seat switch l 2.He then buckles his belt, switching the arm 16b to the terminal 16d andapplying a pulse of current through the capacitor C to the relay coil1140. This switches the arm 1141' to apply the required battery voltagethat closes the starter interlock 120. At the sametime, the arm '114bcompletes a holding circuit for the coil 1140 through the line 19, thecontact 16c and the arm 16a.

An attempt to defeat this arrangement by maintaining the seat beltbuckled will, for the same reasons as in the FIG. 1 embodiment, preventthe pulsing of the relay 114 that is necessary to effect initialswitching of the arms l'l4fand 1141;.

Opening the seat belt during vehicle operation will connect voltagethrough'contact 16a and line 17 to the warning system that includes thelight 24 and buzzer What is claimed is:

1. In a vehicle seat belt and starter interlock system wherein theinterlock has an enabling state that enables the start switch to startthe motor and a disabling state the state of the interlock being afunction of the state of the electrical input applied, from anelectrical source, to an input to the interlock, the improvement forassu'r ing that the seat belt isfastened subsequent to the passengerseating himself in the vehicle, comprising:

a seat switch having a first state when no passenger is seated andhaving a second state in response to the seating of a passenger in theseat involved,

a first seat belt actuated switch having a first state when the seatbelt is unbuckled and having a second state when the seat belt isbuckled,

a second seat belt actuated switch responsive to the process of bucklingthe seat belt to change state during said process, v

a relay switch having a first state and a second state,

said relay switch having an actuating input,

' a capacitor electrically coupled between said actuating input of saidrelay switch and said second seat belt actuated switch, said change ofstate of said second seat belt actuated 1 switch providing an electricalpulse through said capacitor toforce said relay into its second state,and a holding circuit to hold said relay in its second state, theholding circuit including said seat switchand said first seat beltactuated switch, said holding cir- Y cuit being open when said seatswitch is in its first state or when said first seat belt actuatedswitch is in its first state, i

said second state of said seat switch in combination with said firststate of saidrelay switch providing a first state electrical input atthe interlock to cause the interlock to be maintained in its disablingstate.

2. The interlock system of claim 1 wherein:

said first seat belt actuated switch is switched fromits first state toits second state during the buckling of said seat belt at a point intime no later than when said second seat belt actuatedswitch changesstat during the process of buckling. 3. The interlock system of claim 1further comprising: Y a warningsystem operablewhen the'vehiclev is in apredetermined drive state,

- said second state of seat switch in combination with said first stateof said first seat belt actuated switch causing said warning system tobe actuated.

4. The interlock system of claim 2 further comprising: I

a warning system operable when the predetermined drive state, saidsecond state of seat switch in combination with said first state of saidfirst seat belt actuated switch causing said warning system to beactuated. 5. The interlock system of claim 1 further comprismg: I

vehicle is in a that prevents the start switch from starting the motor,

time delay means to hold said relay in its second state for apredetermined time period after said holding circuit is opened. 6. Theinterlock system of claim 2 further comprismg:

time delay means to hold said relay in its second state for apredetermined time period after said holding circuit is opened. 7. Theinterlock system of claim 3 further comprismg:

time delay means to hold said relay in its second state for apredetermined time period after said holding circuit is opened. 1

8. The interlock system of claim 4 further compris- 1 ing:

time delay means to hold said relay in its second state for apredetermined time period after said holding circuit is opened.

9. In a vehicle seat belt and starter interlock system wherein anormally closed interlock is opened by an said seat switch when closedand said first seat belt actuated switch when in said first stateproviding a path between the source of voltage and the inter 'lock toopen the interlock,

a relay switch having a first state and a second state,

said relay switch having an actuating input,

said seat switch when closed,'said first seat belt actu ated switch whenin said second state and said relay switch when in said first stateproviding a path between the source'of voltageand the input to theinterlock to open the interlock,

a second seat belt actuated switch responsive, to the process ofbucklingthe seat belt to change state during said process, a capacitorelectricallycoupled between said actuating input of said relay switchand said second seat belt actuated switch, said change of state of saidsecond seat belt actuated switch providing an electrical pulse throughsaid capacitor to force said relay into its second state,

and a holding circuit to hold said relay in its second state, theholding circuit including said seat switch and 5 said first seat beltactuated switch,

said holding circuit being open when said seat switch is open or whensaid first seat belt actuated switch is in its first state. 1 10. Theinterlock system of claim 9 wherein: said first seat belt actuatedswitch is switched from its first state to its second state during'thebuckling of said seat belt at a point in time no later than when saidsecond seat belt actuated switch changes state during the process ofbuckling. 11. The interlock system of claim 9 further compris- Inga.warning system operable when the vehicle is in a predetermined drivestate, said second state of seat switch in combination with said firststate of said first seat belt actuated switch causing said warningsystem to be actuated. 12. The interlock system of claim 10 furthercomprising: q

a warning system operable when the vehicle is in a predetermined drivestate, said second state of seat switch is in combination with saidfirst state of said first seat belt actuated switch causing said warningsystem to be actuated. 13. The interlock system of claim 9 furthercomprising: g

time delay means to hold said relay inits second state for apredetermined time period after said holding circuit is opened. a a 14.The interlock system of claim 10 further comprising: a I a time delaymeansto hold said relay in its second state for a predetermined timeperiod after said holding circuit is opened. 15. The interlock system ofclaim 11 further com- 40 prising:

time delay means to hold said relay in its second state circuit isopened. v v 16. The interlock system of claim 12 further comprising: I Ttime delay means to hold said relay in its second state for apredetermined-time period after said holding circuit is opened. 7

l t I! for a predetermined time period after said holding

1. In a vehicle seat belt and starter interlock system wherein theinterlock has an enabling state that enables the start switch to startthe motor and a disabling state that prevents the start switch fromstarting the motor, the state of the interlock being a function of thestate of the electrical input applied, from an electrical source, to aninput to the interlock, the improvement for assuring that the seat beltis fastened subsequent to the passenger seating himself in the vehicle,comprising: a seat switch having a first state when no passenger isseated and having a second state in response to the seating of apassenger in the seat involved, a first seat belt actuated switch havinga first state when the seat belt is unbuckled and having a second statewhen the seat belt is buckled, a second seat belt actuated switchresponsive to the process of buckling the seat belt to change stateduring said process, a relay switch having a first state and a secondstate, said relay switch having an actuating input, a capacitorelectrically coupled between said actuating input of said relay switchand said second seat belt actuated switch, said change of state of saidsecond seat belt actuated switch providing an electrical pulse throughsaid capacitor to force said relay into its second state, and a holdingcircuit to hold said relay in its second state, the holding circuitincluding said seat switch and said first seat belt actuated switch,said holding circuit being open when said seat switch is in its firststate or when said first seat belt actuated switch is in its firststate, said second state of said seat switch in combination with saidfirst state of said relay switch providing a first state electricalinput at the interlock to cause the interlock to be maintained in itsdisabling state.
 2. The interlock system of claim 1 wherein: said firstseat belt actuated switch is switched from its first state to its secondstate during the buckling of said seat bElt at a point in time no laterthan when said second seat belt actuated switch changes state during theprocess of buckling.
 3. The interlock system of claim 1 furthercomprising: a warning system operable when the vehicle is in apredetermined drive state, said second state of seat switch incombination with said first state of said first seat belt actuatedswitch causing said warning system to be actuated.
 4. The interlocksystem of claim 2 further comprising: a warning system operable when thevehicle is in a predetermined drive state, said second state of seatswitch in combination with said first state of said first seat beltactuated switch causing said warning system to be actuated.
 5. Theinterlock system of claim 1 further comprising: time delay means to holdsaid relay in its second state for a predetermined time period aftersaid holding circuit is opened.
 6. The interlock system of claim 2further comprising: time delay means to hold said relay in its secondstate for a predetermined time period after said holding circuit isopened.
 7. The interlock system of claim 3 further comprising: timedelay means to hold said relay in its second state for a predeterminedtime period after said holding circuit is opened.
 8. The interlocksystem of claim 4 further comprising: time delay means to hold saidrelay in its second state for a predetermined time period after saidholding circuit is opened.
 9. In a vehicle seat belt and starterinterlock system wherein a normally closed interlock is opened by aninput voltage to the interlock from a source of voltage, the interlockwhen opened prevents the start switch from starting the motor, theimprovement for assuring that the seat belt is fastened subsequent tothe passenger seating himself in the vehicle, comprising: a normallyopen seat switch that closes in response to the seating of a passenger,a first seat belt actuated switch having a first state when the seatbelt is unbuckled and having a second state when the seat belt isbuckled, said seat switch when closed and said first seat belt actuatedswitch when in said first state providing a path between the source ofvoltage and the interlock to open the interlock, a relay switch having afirst state and a second state, said relay switch having an actuatinginput, said seat switch when closed, said first seat belt actuatedswitch when in said second state and said relay switch when in saidfirst state providing a path between the source of voltage and the inputto the interlock to open the interlock, a second seat belt actuatedswitch responsive to the process of buckling the seat belt to changestate during said process, a capacitor electrically coupled between saidactuating input of said relay switch and said second seat belt actuatedswitch, said change of state of said second seat belt actuated switchproviding an electrical pulse through said capacitor to force said relayinto its second state, and a holding circuit to hold said relay in itssecond state, the holding circuit including said seat switch and saidfirst seat belt actuated switch, said holding circuit being open whensaid seat switch is open or when said first seat belt actuated switch isin its first state.
 10. The interlock system of claim 9 wherein: saidfirst seat belt actuated switch is switched from its first state to itssecond state during the buckling of said seat belt at a point in time nolater than when said second seat belt actuated switch changes stateduring the process of buckling.
 11. The interlock system of claim 9further comprising: a warning system operable when the vehicle is in apredetermined drive state, said second state of seat switch incombination with said first state of said first seat belt actuatedswitch causing said warning system to be actuated.
 12. The interlocksystem of claim 10 further comprising: a warning system operablE whenthe vehicle is in a predetermined drive state, said second state of seatswitch is in combination with said first state of said first seat beltactuated switch causing said warning system to be actuated.
 13. Theinterlock system of claim 9 further comprising: time delay means to holdsaid relay in its second state for a predetermined time period aftersaid holding circuit is opened.
 14. The interlock system of claim 10further comprising: time delay means to hold said relay in its secondstate for a predetermined time period after said holding circuit isopened.
 15. The interlock system of claim 11 further comprising: timedelay means to hold said relay in its second state for a predeterminedtime period after said holding circuit is opened.
 16. The interlocksystem of claim 12 further comprising: time delay means to hold saidrelay in its second state for a predetermined time period after saidholding circuit is opened.